The Taliban had just seized control of the country in August and many Afghans were desperately trying to flee.
Two-month-old Sohail Ahmadi was handed to an American soldier over a fence, to protect him from the crush as thousands pushed to get into Kabul airport.
But once his family were inside, Sohail was nowhere to be found.
After a frantic but futile search for the infant, his father Mirza Ali Ahmadi, who had worked as a security guard at the US embassy, mother Suraya and their four other children were put on an evacuation flight to the US.
For months they had no idea where their young son was.
But after reading a Reuters report on the family's search for Sohail, in November he was traced to the home of a 29-year-old taxi driver named Hamid Safi.
Mr Safi said he had found Sohail alone and crying on the ground at the airport, the news agency said. After trying to find the boy's family, he decided to take him home to his wife and children, and raise him as his own son.
They named the infant Mohammad Abed and posted pictures of all the children together on Mr Safi's Facebook page.
When Sohail's whereabouts were confirmed, the baby's grandfather, Mohammad Qasem Razawi, who lives in the north-eastern province of Badakhshan, made a long journey to Kabul to ask for the child to be returned.
However, Mr Safi refused to hand the baby over and demanded he and his family also be evacuated to the US, according to Reuters.
After seven weeks of negotiations - and a brief detainment of Mr Safi - Taliban police arranged a settlement between the two families and the baby was returned to his grandfather on Saturday, Reuters reported.
His parents said they were overjoyed after watching the reunion via video chat.
"There are celebrations, dance, singing," Mr Razawi said. "It is just like a wedding indeed."
They hope arrangements will soon be made for Sohail to be brought to them in the US state of Michigan, where they have now settled.